Dihalopyrazine and especially 2,5-dihalopyrazines are well known materials useful as nitrification inhibitors, and as intermediates in the preparation of insecticides, artificial fibers, detergents and ionic resins as taught in U.S. Pat. Nos. 2,524,431; 2,573,268 and Japanese Pat. No. 17,605/1966.
These compounds can be prepared by a variety of methods including vapor phase halogenation at elevated temperatures with or without the presence of a catalyst and reactions of 3-chloropyrazine-1-oxide with phosphoroyl chloride. Other methods of preparation are continually being sought.